After weeks in which events in Syria took a back seat to the US presidential election campaign, Washington confirmed that the first US troops and equipment had arrived at Incirlik, an air-base in south-eastern Turkey.

Other western troops were photographed by Turkish media landing at Gaziantep airport, near the Syrian border and a short drive from Aleppo, the country’s biggest city.

American, German and Dutch troops will be staffing six batteries of Patriot missiles, to be stationed on the border at Turkey’s request to deter Syrian attacks close to or over the frontier. Their defensive use has been stressed, but their deployment comes in the wake of renewed criticism by the Syrian opposition of the West’s failure to intervene on its behalf, particularly against the regime’s aerial attacks.